[FFmpeg-user] -pix_fmt yuv420p and deinterlacing

[Katherine Frances]

Marton, thank you very much, this is extremely helpful.

Okay, I guess that the output MP4s are actually interlaced, despite the
video stream metadata that MediaInfo reads. Do you think that 'progressive'
is default for libx264 and that's why this metadata property is being added
erroneously?

Lastly, do you know how I can determine whether the file actually is
interlaced?

Thank you!
Best, K


On Sun, Feb 26, 2017 at 11:35 AM, Marton Balint <cus at passwd.hu> wrote:

>
> On Sun, 26 Feb 2017, Katherine Frances wrote:
>
> Hi Martin,
>>
>> Oh! Thanks for letting me know. I just assumed the conflation of the two
>> things here.
>>
>> But then, how are my output videos becoming deinterlaced?
>>
>
> Probably they are not.
>
>
>> Inputs are uncompressed v210 in MOV. They're definitely interlaced, as
>> they're digitized from an analogue source (using an AJA ADC) with all
>> correct setup.
>> And outputs are definitely progressive, at least according to MediaInfo.
>>
>
> Mediainfo only shows the metadata, in reality the content is most probably
> interlaced.
>
>
>> I'm just using a basic script, for example:
>>
>> ffmpeg -i uncompressed_master.mov -c:v libx264 -pix_fmt yuv420p -c:a
>>
>>> libfdk_aac -b:a 128k access_copy.mp4
>>>
>>
>>
>> So how are my MP4s becoming deinterlaced? Is it a result of declaring MP4
>> as the output container? I thought that MP4s could contain interlaced
>> content - am I wrong about that?
>>
>>
> AFAIK ffmpeg does not do automatic deinterlacing based on container
> features, so even if MP4 were progressive-only (it is not), ffmpeg still
> would not do automatic deinterlacing.
>
> The fact that the interlaced metadata is not reflected in the output can
> be caused by a number of reasons, either the source file is missing the
> interlaced/progressive metadata as well, or ffmpeg simply does not support
> propagating it to mp4.
>
> In any case, if you want to deinterlace, use a filter, like yadif.
>
>
> Regards,
> Marton
>
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